EFFECT OF LOW ZINC INTAKE DURING PREGNANCY ON PLASMA PROLACTIN, PROGESTERONE, PROSTAGLANDIN, CORTISOL AND PROTEIN CONCENTRATIONS OF EWES DURING THE PERIPARTURIENT PERIOD

1986 ◽  
Vol 66 (3) ◽  
pp. 643-651 ◽  
Author(s):  
J. A. FITZGERALD ◽  
G. A. EVERETT ◽  
J. APGAR
Keyword(s):  
Plasma Concentrations ◽  
Normal Pregnancy ◽  
Late Gestation ◽  
Plasma Prolactin ◽  
Plasma Parameters ◽  
Zinc Intake ◽  
Periparturient Period ◽  
Prostaglandin F ◽  
The Mean ◽  
Pregnant Ewe

The effect of low dietary Zn intake upon several plasma endocrine and metabolic profiles was examined during late gestation in the ewe. Thirty adult, primiparous Finncross ewes were fed a low Zn diet with (+Zn, n = 14) or without (0Zn, n = 16) supplemental Zn in the drinking water starting day 1 of pregnancy. Although the mean prepartum progesterone and prolactin concentrations were lower (P < 0.05 and P < 0.01, respectively) in 0Zn than in +Zn ewes, the peak prolactin concentrations in 0Zn ewes at lambing were similar to +Zn ewes. Both basal and thyrotropin-releasing-hormone (TRH)-induced prolactin release were less (P < 0.01) in 0Zn ewes 2 d postpartum. Plasma concentrations of 13, 14-dihydro-15-keto prostaglandin F2α (PGFM) of ewes sampled within 45 min post-lambing were lower (P < 0.05) in 0Zn ewes. There was no difference in cortisol concentrations within 45 min after lambing between 0Zn and + Zn ewes. Plasma protein concentrations in 0Zn ewes were higher (P < 0.01) than those in +Zn ewes during pregnancy. In summary, these data show that low Zn intake in the pregnant ewe affected several endocrine and metabolic plasma parameters associated with normal pregnancy and parturition. Key words: Zinc, parturition, dystocia, feed intake, ovine

Maternal pinealectomy alters the daily pattern of fetal breathing in sheep

1990 ◽  
Vol 258 (1) ◽  
pp. R284-R287 ◽  
Author(s):  
I. C. McMillen ◽  
R. Nowak ◽  
D. W. Walker ◽  
I. R. Young
Keyword(s):  
Time Of Day ◽  
Behavioral Pattern ◽  
Late Gestation ◽  
Once Daily ◽  
Daily Pattern ◽  
Significant Difference ◽  
Fetal Breathing ◽  
Fetal Breathing Movements ◽  
The Mean ◽  
Pregnant Ewe

We have investigated the effect of pinealectomy of the pregnant ewe on the 24-h pattern of fetal breathing activity during late gestation. Fetal breathing movements were recorded during 24-h periods on 18 occasions in 5 pinealectomized ewes and on 24 occasions in 6 pineal-intact ewes between 120 and 145 days gestation. All ewes were fed once daily between 1000 and 1300 h and were kept under a light-dark cycle 12:12 h. There was no significant difference in the mean hourly incidence of fetal breathing movements between the pineal-intact (27.2 +/- 0.5 min/h) and pinealectomized (25.5 +/- 0.6 min/h) groups. However, there was a significant difference in the 24-h profiles of fetal breathing movements in the two groups. The peak incidence of fetal breathing occurred between 1900 and 2000 h in the pineal-intact ewes and between 1200 and 1300 h in the pinealectomized ewes. We conclude that maternal pinealectomy alters the daily pattern of a fetal behavioral pattern and that maternal melatonin may therefore provide the fetus with information about time of day.

Corticotropin-releasing factor in the ovine fetus and pregnant ewe: role of placenta

1991 ◽  
Vol 261 (4) ◽  
pp. R995-R1002 ◽  
Author(s):  
M. Keller-Wood ◽  
C. E. Wood
Keyword(s):  
Adrenocorticotropic Hormone ◽  
Plasma Concentrations ◽  
Late Pregnancy ◽  
Maternal Plasma ◽  
Corticotropin Releasing Factor ◽  
Late Gestation ◽  
Fetal Plasma ◽  
Ovine Fetus ◽  
Arterial Plasma ◽  
Pregnant Ewe

In the sheep, maternal plasma adrenocorticotropic hormone and cortisol are increased in late pregnancy, and fetal plasma cortisol and adrenocorticotropic hormone rise precipitously in late gestation. To test whether the ovine placenta secretes corticotropin-releasing factor (CRF) into either the maternal or fetal circulation, pregnant ewes and their fetuses were prepared with femoral arterial catheters and uterine and umbilical venous catheters. Samples were taken from all sites before and during hypoxia. There was no difference in CRF concentration across the placenta in the mothers or the fetuses under resting or hypoxemic conditions, but maternal and fetal arterial plasma CRF concentrations increased between 128 and 145 days. In a second study, maternal and fetal femoral venous plasma CRF concentrations were measured 1-19 days before spontaneous parturition. The mean concentration increased 8.6 +/- 0.6 pg/ml 11-19 days before parturition to 13.0 +/- 1.0 and 13.2 +/- 1.4 pg/ml in fetuses 4-8 and 1-3 days before parturition, respectively. Maternal plasma concentrations did not significantly increase in the days closer to parturition. These studies demonstrate that there are low but measurable CRF concentrations in fetal and maternal sheep plasma but that these are not the result of tonic placental secretion of CRF.

Observations on the effect of protein intake and stage of gestation on the proportion of urinary nitrogen excreted as urea in sheep

1973 ◽  
Vol 80 (3) ◽  
pp. 363-368 ◽  
Author(s):  
J. J. Robinson ◽  
D. Scott ◽  
C. Fraser
Keyword(s):  
Protein Intake ◽  
Late Gestation ◽  
Direct Result ◽  
Ewe Lambs ◽  
Low Protein ◽  
The Mean ◽  
The Difference ◽  
Pregnant Ewe ◽  
N Requirement ◽  
Urinary Nitrogen

SummaryThe effect of altering the level of protein intake on urea excretion in ewes was assessed in two separate experiments.In Expt 1, 14 pregnant (during the last 20 days of gestation) and 10 non-pregnant ewes were each offered a different level of digested N intake in the range 5–25 g/day. At all levels of protein intake urea N excretion was lower in pregnant than in nonpregnant ewes.In Expt 2, 21 pregnant ewe lambs were each offered one of three diets supplying mean intakes of 83 (T1), 113 (T2) or 147 (T3) g crude protein/day. During the last 100 days of gestation the mean levels of urea N excretion were 6·9, 11·0 and 15·2 g/day for T1, T 2 and T 3, respectively. The corresponding values for urinary N excretion were 9·3, 13·8 and 18·2 g/day. At all levels of protein intake urea N excretion was lower just prior to parturition than 95 days prepartum; the difference was correlated with lamb birth weight and maternal body-weight change.A notable feature of both experiments was the low level of urea N excretion by the pregnant ewes in late gestation, at low protein intakes. It would appear that when energy intake is adequate the decrease in urea N excretion associated with pregnancy is a direct result of an increased N requirement for maternal and/or foetal growth.

Changes in the gene expression of progesterone receptor and prolactin receptor in sow mammary gland between late gestation and lactation

1998 ◽  
Vol 1998 ◽  
pp. 179-179
Author(s):  
H. M. Miller ◽  
W. T. Dixon ◽  
G. R. Foxcroft ◽  
F. X. Aherne
Keyword(s):  
Progesterone Receptor ◽  
Prolactin Receptor ◽  
Plasma Concentrations ◽  
Progesterone Receptors ◽  
Late Gestation ◽  
Rapid Decline ◽  
Plasma Prolactin ◽  
Early Lactation ◽  
Plasma Progesterone ◽  
Receptor Mrna

Lactogenesis is triggered by a rapid decline in plasma progesterone concentration combined with a peak in plasma prolactin concentration; in mice, there is a concurrent loss of mammary progesterone receptors (Haslam and Shyamala, 1980). The aims of this experiment were to determine the pattern of change of progesterone receptor and prolactin receptor mRNA during late gestation and early lactation and to determine whether abundance of mRNA for the two receptors are related to each other, to plasma concentrations of progesterone and prolactin or to piglet performance.

Diurnal variations in plasma concentrations of cortisol, prolactin, growth hormone and glucose in the fetal sheep and pregnant ewe during late gestation

1987 ◽  
Vol 114 (1) ◽  
pp. 65-72 ◽  
Author(s):  
I. C. McMillen ◽  
G. D. Thorburn ◽  
D. W. Walker
Keyword(s):  
Diurnal Rhythm ◽  
Plasma Cortisol ◽  
Plasma Concentrations ◽  
Maternal Plasma ◽  
Diurnal Variations ◽  
Plasma Prolactin ◽  
Fetal Sheep ◽  
Fetal Plasma ◽  
Pregnant Ewe ◽  
Plasma Gh

ABSTRACT We have measured fetal and maternal plasma concentrations of cortisol, prolactin, GH and glucose in samples collected during a 24-h period in 14 animals between 127 and 142 days of gestation. There was a significant increase in both the mean daily plasma cortisol concentration and mean daily coefficient of variation (C.V.) of plasma cortisol concentrations after 135 days of gestation. There was also a significant variation in the fetal plasma cortisol concentrations with a peak occurring at 19.00 h. There was a significant sinusoidal diurnal rhythm in the plasma prolactin concentrations in both the fetal sheep and pregnant ewe and the maximal prolactin concentrations occurred between 19.00 and 23.00 h (fetal) and 21.00 and 01.00 h (maternal). Although no significant diurnal variation was detected in fetal plasma GH concentrations, there was a significant sinusoidal diurnal rhythm in the plasma GH concentrations of the pregnant ewe and the maximal maternal GH concentrations occurred between 21.00 and 01.00 h. Both the fetal and maternal plasma glucose concentrations showed a significant sinusoidal diurnal rhythm. The maximal maternal and fetal glucose concentrations were measured between 21.00 and 01.00 h and between 23.00 and 03.00 h respectively. We have therefore established that diurnal variations in plasma cortisol and prolactin concentrations exist prenatally. Whether the presence of such hormonal rhythms reflects the activity of an endogenous fetal circadian pacemaker remains to be established. J. Endocr. (1987) 114, 65–72

Effects of melatonin and a dopamine agonist and antagonist on seasonal changes in voluntary intake, reproductive activity and plasma concentrations of prolactin and tri-iodothyronine in red deer hinds

1990 ◽  
Vol 125 (2) ◽  
pp. 241-249 ◽  
Author(s):  
J. A. Milne ◽  
A. S. I. Loudon ◽  
A. M. Sibbald ◽  
J. D. Curlewis ◽  
A. S. McNeilly
Keyword(s):  
Dopamine Agonist ◽  
Breeding Season ◽  
Red Deer ◽  
Plasma Concentrations ◽  
Control Group ◽  
Rapid Decline ◽  
Dopamine Antagonist ◽  
Plasma Prolactin ◽  
Melatonin Treatment ◽  
The Mean

ABSTRACT Three experiments were conducted in the period between July and November with non-lactating red deer hinds to describe the effects of treatment with melatonin during this period on voluntary food intake (VFI), the onset of the breeding season, coat changes and plasma concentrations of prolactin and tri-iodothyronine (T3), and to examine whether prolactin mediated the observed effects. In experiment 1, eight animals were treated orally each day with either 10 mg melatonin at 16.00 h or 10 mg melatonin at 16.00 h plus 10 mg domperidone (a dopamine antagonist) given twice daily for 120 days from July; eight animals were maintained as controls. In experiment 2, the same numbers of animals per treatment were used to compare treatments in which 10 mg melatonin or 20 mg bromocriptine (a dopamine agonist) were given orally each day at 16.00 h for 119 days from late June and compared with an untreated control group. In experiment 3, six animals were treated daily for 105 days from mid August with 5 mg domperidone given i.m. and compared with six control animals. In experiments 1 and 2, the VFI of control animals reached a peak in late August and thereafter declined. Melatonin-treated animals showed a similar pattern but the peak in VFI was significantly (P<0·05) advanced by 2 weeks compared with controls, although the VFIs of both groups were similar in November. The mean date of onset of the breeding season of the melatonin-treated animals was advanced significantly (P < 0·05) by 23 days in both experiments and the coats of these animals had less undercoat and were pale coloured and patchy compared with the controls. The changes in VFI, coat and the onset of the breeding season were associated with the rapid decline in plasma prolactin concentration after the start of the melatonin treatment and significantly (P<0·01) lower plasma T3 concentrations than those of control animals. In experiments 1 and 3, plasma prolactin concentrations in animals treated with domperidone were higher than those of controls for periods of 2–3 weeks. These short-term increases in plasma prolactin concentration were not associated with changes in VFI, coat or onset of the breeding season compared with controls. In experiment 2, the pattern of decline in plasma prolactin concentrations was the same in bromocriptine-treated animals as in the melatonin-treated animals; plasma T3 concentrations were also similar in the two groups. The pattern of change in VFI over time in bromocriptine-treated animals was significantly (P<0·05) different from that of melatonin-treated animals and there was also a reduced amount and length of winter coat in the bromocriptine-treated animals. The mean date of onset of the breeding season in bromocriptine-treated animals was not significantly different from that of controls. It was concluded that a reduction in plasma prolactin concentration induced by bromocriptine produced different effects from that induced by melatonin treatment and that the effects of melatonin are unlikely to be induced through changes in contemporary plasma prolactin concentrations. Journal of Endocrinology (1990) 125, 241–249

Plasma concentrations of progesterone, oestradiol-17β and 13,14-dihydro-15-oxo-prostaglandin F2α in the pregnant wallaby (Macropus rufogriseus rufogriseus)

1983 ◽  
Vol 97 (3) ◽  
pp. 369-377 ◽  
Author(s):  
M. T. Walker ◽  
R. T. Gemmell
Keyword(s):  
Plasma Concentrations ◽  
Prostaglandin F2α ◽  
Maternal Plasma ◽  
Gestation Length ◽  
Birth Process ◽  
Plasma Progesterone ◽  
Prostaglandin F ◽  
The Mean ◽  
Uterine Secretions ◽  
Mean Concentration

The concentrations of progesterone and oestradiol-17β in the maternal plasma of Bennett's wallaby, Macropus rufogriseus rufogriseus, were measured daily throughout gestation after reactivation of the diapausing corpus luteum by removal of the suckling pouch young (RPY). Progesterone increased from mean concentrations of 382–424 pmol/l (120–133 pg/ml) during lactation to reach peak concentrations of 908 ± 172 (s.e.m.) pmol/l (285 ± 54 pg/ml) (n = 8) 4 days after RPY and 971 ± 220 and 971 ± 229 pmol/l (305 ± 69 and 305 ± 72 pg/ml) (n = 7) 24 and 25 days after RPY respectively. The mean gestation length (RPY to birth) was 26·8 ± 0·6 (s.d.) days (n = 6, range 25·75–27·50 days). Immediately after birth the plasma progesterone concentration declined to 299 ± 51 (s.e.m.) pmol/l (94 ± 16 pg/ml) (n=6). Oestradiol-17β increased from mean concentrations of 291–553 pmol/l (80–152 pg/ml) during lactation to reach a peak concentration of 967 ± 331 pmol/l (266 ± 91 pg/ml) (n = 9) 1 day after RPY. The concentration declined from 7 days after RPY and fluctuated between mean concentrations of 273 and 480 pmol/l before reaching a minimum of 207 ± 69 pmol/l (57 ± 19 pg/ml) (n = 6) 19 days after RPY. A transient increase to 542 ± 207 pmol/l (n = 7) occurred at 22 days after RPY. Plasma concentrations declined to a low of 156 ± 55 pmol/l (43 ± 15 pg/ml) (n = 6) 5 days after parturition. The mean concentration of plasma 13,14-dihydro-15-oxo-prostaglandin F2α was less than 2·8 nmol/l (1 ng/ml) for all samples from 13 days after RPY until 4 days after parturition. The results suggest that oestradiol-17β may be important in the early stages of blastocyst reactivation to synergize with progesterone in stimulating uterine secretions. 13,14-Dihydro-15-oxo-prostaglandin F2α is unlikely to be involved in the birth process and any luteolytic effect is likely to be from a local production of PGF2α.

EFFECTS OF MATING ON LEVELS OF OXYTOCIN AND PROLACTIN IN THE PLASMA OF MALE AND FEMALE RABBITS

1981 ◽  
Vol 90 (2) ◽  
pp. 245-253 ◽  
Author(s):  
ANNA-RIITTA FUCHS ◽  
LINDA CUBILE ◽  
M. Y. DAWOOD
Keyword(s):  
Plasma Levels ◽  
Plasma Concentrations ◽  
Plasma Prolactin ◽  
Male And Female ◽  
Uterine Activity ◽  
Random Fashion ◽  
Transient Rise ◽  
Cardiac Catheters ◽  
Large Fluctuations ◽  
The Mean

The effects of mating on plasma levels of oxytocin and prolactin in male and female rabbits have been investigated. Blood was collected through indwelling cardiac catheters at intervals of 1, 2, 4, 6, 12, 24, 36 and 60 min after mating. In female rabbits additional samples were taken 5 h after mating, as well as daily during the ensuing pregnancy or pseudopregnancy. They were also fitted with intrauterine balloons for recording uterine activity. Copulation induced a rapid, transient rise in plasma oxytocin in female rabbits at the same time as a fall in plasma prolactin. Mating or sexual excitement had no significant effect on plasma concentrations of oxytocin or prolactin in bucks. Relatively large fluctuations of plasma oxytocin were seen in male rabbits under normal conditions and after mating, suggesting episodic release of oxytocin in a random fashion. The uterine recordings indicated that, in spite of the modest release of oxytocin, a strong sympathetic adrenal activation occurred in response to mating and this provided the overriding influence on uterine activity. During pregnancy plasma levels of prolactin rose significantly on day 4, and remained raised throughout most of gestation. Plasma prolactin fluctuated widely during the first half of pregnancy but the mean levels were higher than those found during the second half of gestation. When pseudopregnancy was induced with injection of an ovulating dose of LH, plasma prolactin rose in a similar manner as during early gestation or mating-induced pseudopregnancy. Thus, in contrast to rats, stimuli associated with mating have no direct influence on the subsequent release of prolactin in rabbits. The secretion of prolactin during gestation seems to be controlled entirely by ovarian steroids, probably progesterone.

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